In a study of 67 teenagers, researchers have discovered that the timing of the brain’s maturing is closely related to puberty in teenagers.
The study used electroencephalogram (EEG) measures of the brain together with physical indicators of puberty to show a link in the development of the systems that control behavior and reproduction.
The researchers believe the outcome could lead to studies that reveal markers of brain abnormalities that contribute to mental illness — such as schizophrenia and bipolar disorder — that first become apparent during adolescence.
“A connection between brain and body maturity has long been suspected, but demonstrating its existence has been difficult,” said Ian Campbell, project scientist in psychiatry and behavioral sciences at UC Davis and senior author of the study.
“Because we were able to track both processes within a large group of teenagers over the course of the crucial years of adolescence, we could demonstrate this association. Exploring the mechanisms that underlie this relationship could ultimately help us better understand the mental-health issues of teenagers.”
In previous research, Campbell and colleagues showed that EEG activity declined sharply — by more than 60 percent — during adolescence.
They attributed this decline to a reduction of neuronal activity due to synaptic pruning as the brain advances toward adulthood. Their new study shows that this process is time-linked to the progression of puberty. Boys and girls in the study who went through puberty earlier also showed an earlier decline in EEG activity.
For the current study, the team evaluated 67 healthy adolescents — 34 girls and 33 boys — with twice-yearly nighttime EEGs, which record fluctuations in electrical activity within the brain’s neurons.
One group of participants began the study at age 9 and was evaluated through age 16, and another group entered the study at age 12 and was evaluated through age 18.
Within a month of each child’s EEG, his or her stage of puberty was determined by a physician using the Tanner scale of breast development in girls and genital development in both boys and girls.
The results showed that EEG fluctuations during nonrapid eye movement sleep — when the brain is most recuperative — declined for all participants, with the most rapid decline between the ages of 12 and 13 for girls and between the ages of 13 and 14 for boys.
When compared to the Tanner scale results, there was a robust relationship between the timing of this brain change and pubertal development.
Campbell and Feinberg hope their finding inspires research to determine if neuroendocrine events of puberty drive adolescent brain maturation or if these are independent but parallel processes.
“Now that we know the processes are linked in time, we need to determine how,” said Campbell. “There could be one physiologic mechanism of control, or they could just simply have common timing with separate triggers. There is still much more that we need to know about the brain during this critical stage of human development.”
The study was published in the Proceedings of the National Academy of Sciences.
Source: Proceedings of the National Academy of Sciences